Penguin book
1948
1948
1946
1948
1951
1946-1950
1950-1952
1946
1947
1950
1951
1950
1951
circa 1950
1951
2000-100 BCE
1938 and 1951
1947
1946-1948
1948
1946
circa 1950
1946
1955; 1830
1948
1950-1951
1951
1949
1950
1951
1949
1946
1950
1949
1950
1949
1947
circa 1950
circa 1950
1946-1948
1951
1990-96
1951
1951
1951
1951
1948
1949
1947-1948
1950
1801-1892 (prepared); 1946 (element replaced)